“How to keep my knee from popping out of place?”

Suggest seeing Sports Medicine Physician to address role of imaging, physical therapy, bracing and ? Surgery

You should get evaluated by with a Chiropractor or Orthopedic Doctor. There are a number of reasons that your knee is unstable and keeps “popping out of place.” With that being said, many times, especially at your young age, gentle Chiropractic Adjustments along with specific exercises can stable the knee joint and stop it from doing this.

What you have is patellar instability. It happens when the patella "de-tracks" out of the trochlea groove, specifically, a patellar tracking disorder

This condition most commonly affects women.

It occurs from a twisting mechanism with the knee in extension, or with encounter of a direct hit to the knee cap.

Some of the proven ways to prevent the knee for popping out of place is to do the following:
a) taping or bracing - to prevent the de-tracking mechanism
b) orthotic device - to stabilize the tracking mechanism over time
c) quad strengthening - to support the appropriate tracking mechanism

Repeated subluxations (incomplete pop outs) or dislocations (complete pop outs) can further be assessed via imaging, to ensure that no ligaments or tissue destruction have occurred to precipitate the repeated dysfunction.

If your knee cap is popping out of place, you should find out why. Is there a muscular imbalance between the Vastus lateralis and the Vastus Medialis or is there a problem with the femoral condoles? If it is a muscular balance issue, you just need to strengthen the weak side of the thigh by doing the appropriate exercises. I would consult a Chiropractor or physical therapist to get an exam and the right exercise prescription.Good luck

Strengthen your quads, glutes and hamstrings. Quads are the most important. Find a trainer to help you.

Sounds like your knee cap is moving.Need a thorough exam by an orthopedic surgeon.